What I did on my 90 740 is just replace the actual lens w/ e-code o.e. Volvo from fcpgroton.com They don't havethem on line but if you call their toll free #, ask for Nick Bauer as he knows his Bricks. When I bought them about 18 months ago, they were $90 each. What I did was removed the existng plastic lenses; one was half off already but the other one was quite persistent and took me a bit w/ my Dremel and a cut off wheel to cut through what ever sort of mule glue they use. I used clear silicon to attach the new lenses and then bound them up with duct tape for a day. Still nice and tight after 2 Texas summers. Keep in mind, this is not as good as genuine e-code assemblies as you're still using US DOT 9004 bulbs rather than H4's that the Europeans use. Also, you're still using the US plastic reflector/bucket rather than the glass used across the pond. DON"T re-wire your plugs for the H4, you run an excellent chance of melt down. I chose this route as beginning in 90, there are actually 3 different sizes of headlights used in the 7/9 series. I was e-mailing folks over seas and sent them several photos with measurements using a metric ruler and just wasn't willing to a. spend that much and b. risk them being the wrong size. For 89 and earlier models w/ quad lamps you can simply replace your sealed beams w/ composites that use the H4 low beam and H4/H1 high beam. I bought a set of 4 on eBay (made in India) for about $90. The alternative to this would be true e-code headlamps that look very much like the 90+ single head lamps. The whole set up is upwards of $350 and is an easy swap as the cars were designed for them to begin with. That is for new parking assemblies as well as the complete headlights.
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When Volvos are outlawed, only outlaws will have Volvos!!